GGT1 and alcoholic liver diseases: The fractionation of serum GGT by high‐performance gel filtration liquid chromatography can be used for the differential diagnosis of alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD), in which the alcohol metabolite acetaldehyde induces an increase in the expression of GGT, with the highest s‐GGT/t‐GGT ratio and the lowest f‐GGT/t‐GGT ratio in alcoholic liver disease (ALD) [153].